Last month, we looked at an emerging debate amongst materials scientists over the nature of a new form of carbon that was recently discovered by compressing graphite at room temperature to pressures in excess of 10 GigaPascals.

Under these conditions, various properties of graphite change, such as its resistivity, optical transparency, reflectance and so on. That's a good indication that something different is forming.

But the question is what?  Various groups have proposed new carbon allotropes that could explain the results. These are variously called monoclinic M-carbon, cubic body center C4 carbon, orthorhombic W-carbon and most recently M10-carbon

Today, Chaoyu He and buddies at the Institute for Quantum Engineering and Micro-Nano Energy Technology in Xiangtan, China, propose two new superhard structures, which they call S-carbon and H-carbon.

To read more, click here.